1. Field of the Invention
The present invention relates to devices and methods using pulse density modulation, especially to an electronics device, a communication method, an audio device and an amplifying device using pulse density modulation for communication.
2. Description of Related Art
Pulse density modulation (PDM) is a modulation technique to express an analog signal by a stream composed of many one-bit digital signals. Unlike pulse code modulation (PCM) which evaluates analog signals of different amplitudes by distinct multi-bits digital signals, pulse density modulation shows the strength of an analog signal by the density of said one-bit digital signals.
Generally speaking, a pulse density modulation interface is quite simple, which is composed of a clock pin and a data pin and usually applied to an audio device. Said clock pin can transmit a clock signal; and said data pin can transmit signals of left and right sound channels in light of the rising and falling edges of the clock signal respectively. Because of the simple hardware frame of pulse density modulation, a former pulse density modulation interface is limited to data transmission with no control function in the early days, but the state of the art has allowed the pulse density modulation interface to transmit a specific data pattern for write control; more specifically, a modern pulse density modulation interface is capable of transmitting digital data in a specific pattern (e.g. 11000101 or 10010101 repeating for 64 times) according to the periodic change of the foresaid clock signal, so as to control a reception end to perform a write process in accordance with the digital data (e.g. 11000101 repeating for 64 times indicating that a value “1” should be written down, and 11000101 repeating for 64 times indicating that a value “0” should be written down). However, this control method can only manipulate a predetermined component in the reception end, but can't choose a component in interest to perform a write process; moreover, the control method only allows a transmission end to control a reception end in a unidirectional way, which means that the reception end is not able to provide data for the transmission end reversely.